Waste heat boiler



Ag.. 1938. c. v. MCINTIRE Ef AL WASTE HEAT BOILER `Filed April 14, 1934l Patented Aug. 9, 1938 WASTE HEAT BOILER,

Charles V. Mclntire, Short Hills, N. Ji., andLloyd F. Schrader, Bellerose, N. Y., assignors to Semet-Solvay Engineering Corporation, York, N. Y., a corporation of New York New `Application April 14, 1934,'Se1ial N0.720,538

Claims.

This invention is directed to waste heat recovery apparatus, and, more particularly', to a waste heat boiler for use in connection with a water .gas set and adapted to be heated by blast 5 gases from the set during the blasting cycle and by heat generated in an auxiliary fluid fuel fired unit during the water gas making cycle.

I-Ieretofore, it has been proposed to employ a waste heat boiler to receive blast gases from a water gas set during the blasting cycle and during the water gas making cycle to be heated by products of combustion generated in a combustion chamber such as a Dutch oven. To prevent overheating of the brick work of the combustion chamber or Dutch oven,` air was circulated through a jacket surrounding the brick work. In order to maintain a reasonably low fiame temperature in the combustion chamber, a large excess of air was introduced to support the combus- Without such excess of air, fluxing of the refractory lining would take place. While the air passed into the combustion chamber serves as a carrying medium for delivering heat to the boiler, anexcess of air necessarily results in an in-V creased volume of stack gases with resultant increased heat losses. l

An objectoi the present invention is to provide a combined waste heat boiler and combustion chamber which is more economical to construct and which isr more eiiicient in operation. Other objects and advantages of this invention will appear from the following detailed description.

In accordance with this invention, a waste heat boiler, such for example as the vertical type waste heat'boiler provided with an upright boiler drum communicating'with ai steam and water drum, is equippedwith a water jacketed combustion chamber. Products of combustion generated in the combustion chamber may be passed through the 4boiler drum during the`water gas making cycle to supply the heat necessary to generate steam. The water jacketed portion of the combustion' chamber is communicably connected with the steam and water drum and also the boiler drum so that the circulation of water takes place` from the boiler drum through the water jacket into and through the steam and water drum, back to thel boiler drum. Due to this circulation, the combustion chamber jacket becomes part of the boiler and the inner shell of the combustion chamber serves as an active steam generating surface.V

A considerable amount of heat is absorbed in the water jacket by direct radiationV `from the tion of the oil or other liquid fuel burned.y

flame resulting from Vthe combustion of oil or other iiuid fuel. This serves the useful purpose of generating steam in the jacket and at the same time results in a tempering of the gaseous productsof combustion which are passed to the boiler from the combustion chamber. Cooling of the gaseous products of combustion thus effected minimizes, if it does not eliminate, loosening of the tubes in the upper tube sheet of the boiler due to overheatingof the tube sheet, and deterioration of the brick lining in the duct or passageway connecting the water jacketed combustion chamber with the waste heat boiler caused by overheating of the brickwork with `consequent surface fusion and slagglllg.

Among the important advantages of the combined water, jacketed combustion chamber and waste heat boiler, as compared with the aircooled Dutch ovens heretofore employed, the following may be mentioned.

(l) Higher thermal eiiiciencies due to direct exposure of the heated surfaces of the water jacket to high temperature radiation from the flames produced in the combustion chamber and also due to a reduction in stack losses;

(2) Lower operating costs due to elimination of brick lining upkeep expense and increased life of the tube sheets; and

(3) The equipment is more simple in design and can be constructed at lower costs.

In the preferred embodiment illustrated on the drawing, the invention is shown incorporated in a water gas set equipped with a combined waste heat boiler and water jacketed combustion chamber and the present disclosure'will be confined to the present illustrated embodiment of the invention. It will be understood, however,that the novel features and improvements are susceptible to other applications, such for example as other types ofV boilers thanthe vertical type shown in the drawing. Hence, the scope of this invention is not confined to the embodiment herein described.

In the accompanying drawing, forming a part of this specification and showing for purposes of exempliiication a preferred form of this invention without limiting the claimed invention to such illustrative instance, the single iigure is a side elevation, partly broken away, of a water gas set equipped with the `waste heat boiler and combined water jacket embodying this invention.-

In the drawing, reference numeral Il] indicates a water gas generator having a bed of fuel Il which may be of coalor coke. The generator IIJ communicates` with the carburetor I2 by means of connection I3 disposed to connect the top of the generator with the top of the carburetor. Carburetor I2 may be provided with checkerbrick I 4 as is customary and communicates by means of passage I5 with the superheater I6 provided with checkerbrick I1. The top of the superheater is provided with a blast cap I8 arranged to be operated by hydraulic cylinders I9 of any Well known type. As customary, a stack 20 is disposed above the superheater. A line 2I leads from the superheater into housing 22.'

Backrun line 23 leads from Vthe bottom, of the generator beneath the grate to the housing 22.

A three-way valve 24 is disposed in the housing 22 and is arranged to interrupt the flow from the line 2I into the housing 22 and simultaneously permit iiow from backrun line 23 into the housing and vice versa. Operation of the` three-Way valve 24 may be accomplished by a rack and ratchet mechanism indicated generally by the reference numeral 25, the rack being actuated by a hydraulic cylinder or motor 25. Housing 22 communicates by'rnean's of pipe 21 with washbox 28 provided with an offtake 48 leading to a holder or other suitable point.

Air for blasting and secondary air for supporting combustion of the'blast gases maybe admitted to the generator through lines 3l and 32, respectively. These two lines are supplied from the main linev33 and flow of the blasting air and secondary air controlled by valves 34, 35 which are arranged to be operated by hydraulic cylinders 36, 31. AV valve 4I operated'by hydraulic cylinder 42 controls the flow of uprun steam through pipe line 19 leading into the base of the generator. 'A like valve 43 controlled by hydraulic cylinder 44 controls the flow of backrun steam into the superheater. Flow of oil into the carburetor may be controlled by hydraulically operated valve 45.

The top of the superheater is connected by a 'passage 49 with the top of the waste heat boiler 50. A valve 5I in passage49 controls flow therethrough and operation of valve 5I may be effected by hydraulic cylinder 52. `The waste heat boiler may be o f any well knowntype but preferably is of the fire tube type and/'as indicated on the drawing may comprise tube sheets 53, 54 in which the tubes 55 are disposed in the manner well known in the boiler art. The tube and tube sheets are mounted in the boiler drum 56 inclined somewhat to the vertical as shown in the drawing. A steam and water drum 51 is disposed to one side and somewhat above the top of the boiler drum 56. This drum 51 may be supported ona bracket extending from the top of the boiler drum. 'Ihe base portion of the steam and water drum has leading therefrom one or more downcomer tubes 58 which connect the bottom of the steam and Water drum with the base portion of the boiler drum 56. One or more upcomer tubes 59 may be employed to connect the steam and water drum with the top portion of the boiler drum 56. Circulation of water takes place from the top of boilerdrum 56'through tubes 59 into the steam and water drum 51, then through tubes 58 intro the base portion of the boiler drum 56. The base portion of the vertical drum 56 beneath Ythe tube sheet 54 is formed with Va gas outlet l6I which communicates with a stack 62.

.,In accordance with this invention, a water jacketed combustion chamber 63 is placed in communication with the gas flue 64 leading into the 'gas inlet of the waste heat boiler 50. The

combustion chamber is preferably disposed somewhat below the steam and water drum 51. It may be composed of an inner metal corrugated shell 65 and an outer metal shell 66 forming a space for the reception of liquid preferably Water. A refractory lined flue 61 connects the combustion chamber with the gas inlet 64 of the Waste heat boiler. A fluid fuel burner such as an oil or gas burner 68 extends into the combustion chamber.

.Flow of iluid fuel such as oil to this burner is controlled by a valve 69 of any well known type, operation of which may be effected by hydraulic cylinder 'I I. Air is supplied to the burner by a blower 11 communicating with a line 18 extending into the combustion chamber 63. A Valve 46 in line 18 controls the flow of air under pressure to the burner. Operation of Valve 46 may be effected by a hydraulic cylinder 41.

Leading from the base of the boiler drum 56 is a pipe provided with branched extensions 1I extending into the water jacket. The upper portion of the water jacket is preferably provided with a plurality of conduits 12 connecting the water jacket-with the steam and water drum 51.

YEach of the hydraulic cylinders controlling the valves for admitting air and steam to the fuel bed, oil to the carburetor, flow of blast gases through the waste heat boiler, ow of gas through thefset and the flow of air and oil to the water jacketed combustion chamber is supplied with pressure fluid from a common source. The flow of pressure fluid to these hydraulic cylinders and the discharge of the pressure fluid therefrom is controlled from a central control nest 13 which may be of any Well known type. As shown on the drawing, the control nest may involve a shaft 14 rotating at substantially'constant speed and provided with a series of cams, one for each hydraulic cylinder, and'arranged to operate valve mechanism controlling the ow of pressure iluid to and the discharge of pressure fluid from each hydraulic cylinder. Such valve mechanisms may be of any type well known in the gas art and are indicated diagrammatically on the drawing by the reference numeral 15. The lines connecting each hydraulic cylinder with the valves are indicated by the reference numeral 16. As the control mechanism per se and the connections thereof to the hydraulic cylinder may be of any well known type, this mechanism has been depicted on the drawing somewhat schematically.'

In operation, the fuel bed I I may be blasted with air and the resultant blast gases burned in the carburetor and superheater to heat the checkerbrick therein,V combustion of the blast gases being supported by Secondary air admitted through pipe 32. The products of combustion pass through flue or'line 49 into the waste heat boiler 5D, through the tubes heating the water surrounding the tubes and then through outlet 6I to the stack 62. Upon the completion of the blasting cycle, which may be of approximately two minutes duration, the introduction of air to the set is interrupted. This is accomplished by operation of the control nest which functions to effect closing of the valves controlling the flow of air into the set and also valve 5I which controls flow through uef49 into the waste heat boiler. These valves, it will be understood, were opened to eifect blasting of the fuel bed to permit the flow of blast gases through the waste heat boiler. Concurrently with the closing of the aforementioned valves, the control nest effects the opening of the steam valve 4I for admitting uprun steam to the generator. The steam reacts with the fuel bed to form water gas which passes through the carother fluid fuel to the water jacketed combustion chamber 63. The products of combustion generated pass through flue 61, through the tubes in the waste heat boiler, heating the water surrounding the same and leaves outlet 6I entering stack 62. A considerable amount of heat is absorbed in the water jacket by directv radiation from the llame produced therein. This serves the useful purpose of generating steam in the jacket. As hereinabove indicated the gases formed in the combustion chamber are tempered by the water circulated through the water jacket. Steam produced in the water jacket passes through tubes 12 in the form of steam bubbles entrained in water, and these bubbles lift a relatively large quantity of water through the tubes and discharge it into the steam and water drum 51. Water enters the water jacket through pipe 10, to replace that portion converted into steam and carried by the steam into the steam and water drum 51. The circulation of water thus established causes the combustion chamber jacket to become part of the boiler, the inner shell of the chamber functioning as an active steam generating surface.

At the completion of the uprun cycle, which may be of about two minutes duration, valve 4l and three-way valve 24 are operated, valve 4| being closed and three-way valve 24 being moved into position to close line 2| and open line 23. The backrun steam inlet is simultaneously opened, backrun steam passing through the superheater, carburetor, down through the fuel bed in the generator, the resultant water gases passing through the backrun line into the washbox. Concurrently with this operation, oil or other uid fuel and air are admitted to the combustion chamber and products of combustion pass through the waste heat boiler as hereinabove described. Upon the completion of the backrun cycle, which may be of about one minute duration, the admission of oil and air to the combustion chamber is interrupted, backrun steam inlet closed, three-way valve 24 operated to close line 2l, and the blasting cycle commenced as hereinabove described.

Since diierent embodiments of the invention could be made without departing from the scope of this invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

We claim:

1. In a waste heat boiler, a main upright boiler drum having gas passageways therethrough, a steam and water drum, upcomer means connected to deliver from the upper portion of the main drum to the steam and water drum, downcomer means connected to lead water from the steaml and Water drum to the lower portion of the main drum, a water jacketed fluid fuel fired combustion chamber communicably connected with the upper portion of the main drum, means connecting the water jacket with the lower portion of the main drum and with the steam and water drum for circulation of Water from the main drum through the Water jacket into and through the steam and water drum, and means for burning fluid fuel in the combustion chamber and conducting the products of combustion therefrom through the main drum.

2. A Waste heat boiler comprising, in combination, a drum adapted to contain liquid, means for generating and passing hot gases through said drum from one end to the other thereof to heat said liquid by heat exchange therewith, a liquid jacketed combustion chamber, other means for generating products of combustion in said combustion chamber and passing the same through said drum along the path traversed by said hot gases and tubes connecting said jacket with said drum for passing liquid from said jacketed combustion chamber to said drum.

3. A waste heat boiler comprising, in combination, a drum having re tubes therein extending from one end to the other end thereof and adapted to contain liquid surrounding said tubes, means for passing waste gases through said tubes to heat said liquid by heat exchange therewith, a combustion chamber, a liquid jacket substantially surrounding said combustion chamber, and means for generating products of combustion in said combustion chamber and passing the same through said tubes, said liquid jacket being connected to said drum by means including tubes whereby liquid is circulated through said jacket and said drum.

4. A waste heat boiler comprising, in combination, a boiler drum having tubes therein and adapted to contain liquid surrounding said tubes, a steam drum communicably connected to said boiler drum by tubes, means for passing waste gases through said rst mentioned tubes to heat said liquid by heat exchange therewith, a liquid jacketed combustion chamber communicably connected to said boiler drum by upcomer and downcomer tubes, whereby liquid recirculates between said drums and chamber, and means for generating combustion gases within said chamber and passing them through the tubes in said boiler drum.

5. A waste heat boiler comprising, in combination, a boiler drum, a vapor drum, tubes communicably connecting said vapor drum with the boiler drum for circulation of liquid therebetween, a liquid jacketed combustion chamber located exteriorly of said boiler drum, tubes connecting said liquid jacket with said boiler drum and said Vapor drum for circulation of liquid therebetween, means for communicably connecting said combustion chamber with said boiler drum for passage of products of combustion from said chamber through said boiler drum, and means for burning liquid fuel in said combustion chamber.

CHARLES V. MCINTIRE. LLOYD F. SCHRADER. 

